An abundant and low toxicity iron catalyst has enabled regioselective annulation of alkenes with α-halocarboxylic acids and their derivatives. The reaction proceeds smoothly without any additional ligands, bases, and additives to afford a variety of γ-lactones in good yields. A proposed reaction pathway through radical annulation is supported by some mechanistic studies, involving radical clock and
Addition of carboxylic acid dianions appears to be a potential alternative to the use of aluminium enolates for nucleophilic ring opening of epoxides. These conditions require the use of a sub-stoichiometric amount of amine (10% mol) for dianiongeneration and the previous activation of the epoxide with LiCl. Yields are good, with high regioselectivity, but the use of styrene oxide led, unexpectedly
One-Pot Quinine-Catalyzed Synthesis of α-Chiral γ-Keto Esters: Enantioenriched Precursors of <i>cis</i>
-α,γ-Substituted-γ-Butyrolactones
作者:Sara Meninno、Chiara Volpe、Alessandra Lattanzi
DOI:10.1002/adsc.201600427
日期:2016.9.1
enantioselective one‐pot synthesis of important building blocks, α‐chiral γ‐keto esters, has been developed by combining a quinine‐catalyzed Michael addition of malononitrile to trans‐enones followed by magnesium monoperoxyphthalate (MMPP) oxidation. These synthons proved to be useful reagents for a simple access to challenging cis‐α,γ‐disubstituted γ‐butyrolactones in good diastereoselectivity and
Photoinduced umpolung addition of carbonyl compounds with α,β-unsaturated esters enables the polysubstituted γ-lactone formation
作者:Jia-Yi Gu、Wei Zhang、Seth R. Jackson、Yan-Hong He、Zhi Guan
DOI:10.1039/d0cc05306f
日期:——
herein report the photoinduced intermolecular umpolung addition of aromaticketones/aldehydes with α,β-unsaturated esters via ketyl radical intermediates. Following an intramolecular transesterification, a variety of γ-lactone derivatives are readily accessed. Mechanistic investigations demonstrate the significant role of Hantzsch ester, which serves both as the electron and proton donor.